A panel is a collection of recruited individuals who agree to the collection of data related to some aspect of their behavior, usually in return for compensation. Panels may be used for a single media outlet, such as over-the-air broadcast television program viewing, product purchases, and Internet Web browsing. A single source panel (SSP) may combine many different behavioral aspects.
To collect behavioral data, some panel organizations provide specialized software or hardware devices for installation at an individual's residence; presumably, most behavior to be monitored (e.g., Web usage, television program viewing) occurs at the individual's residence.